1. Field of the Invention
This invention relates to a gas turbine apparatus, and more particularly to a exhaust gas recirculating type combined cycle plant wherein exhaust gas is recirculated to an air intake side of a compressor.
2. Description of Related Art
Japanese Unexamined Patent Application No. Hei7-34900 discloses an exhaust gas recirculating type combined plant wherein a part of exhaust gas from a gas turbine is returned to an air intake of a compressor so as to raise a compressor air intake temperature so that a combustion temperature at the time of partial loading or gas turbine exhaust gas temperature is prevented from dropping thereby preventing a drop in cycle heat efficiency at the time of the partial loading.
Further, according to Japanese Unexamined Patent Application No. Sho56-141040, before recirculated combustion gas enters a compressor, water is sprayed so that it is vaporized. A cooling unit is provided on a compression air path out of the compressor and by supplying coolant medium, heat is recovered so that a rate of heat recovery from exhaust gas is improved.
However, the Japanese Unexamined Patent Application No. Hei7-34900 does not disclose anything about widening a range in which high efficiency partial load operation is enabled by stabilized recirculation of exhaust gas. Further, Japanese Unexamined Patent application No. Sho56-141040 does not mention anything about a partial load operation.
The combined cycle plant has such a feature that there exists an atmospheric temperature maximizing its plant efficiency and the plant efficiency drops at other temperatures than the atmospheric temperature.
An object of the present invention is to provide an exhaust gas recirculation type gas turbine apparatus having a wide partial load operation range allowing high efficiency operation.
Another object of the present invention is to provide an exhaust gas recirculation type gas turbine apparatus capable of obtaining a desired output efficiently even when the external temperature changes.
To solve the aforementioned problem, the first invention provides an exhaust gas recirculation type gas turbine apparatus comprising: a compressor for compressing air; a combustion chamber for burning compression air exhausted from the compressor and fuel; a gas turbine driven by gas turbine exhaust gas from the combustion chamber; a recirculation path for recirculating a part of the gas turbine exhaust gas to an intake of the compressor; a recirculation amount control unit for adjusting an amount of gas turbine exhaust gas to be returned to the intake of the compressor corresponding to a change in load of the gas turbine; and a spray unit for introducing liquid droplets into an interior of the compressor in which mixing gas comprising gas turbine exhaust gas passing through the recirculation path and air flows so as to vaporize the introduced liquid droplet during a flow in the compressor.
As a result, air is compressed in the compressor, the compressed air and fuel are burned in the combustion chamber, the gas turbine is driven with gas turbine exhaust gas from the combustion chamber, a part of the gas turbine exhaust gas is recirculated to the intake of the compressor through the recirculation path, the amount of the gas turbine exhaust gas to be returned to the intake of the compressor is adjusted corresponding to a change in the load of the gas turbine, and liquid droplets are sprayed from the spray unit so as to introduce the liquid droplets into the compressor in which mixing gas comprising gas turbine exhaust gas passing through said recirculation path and air flows so that the introduced liquid droplets are vaporized during a flow in the compressor.
Because of vaporizing the liquid droplets in the compressor, a rise of the compressor exit temperature is suppressed so that the temperature of the mixing gas entering the compressor is raised, the recirculation amount can be increased and further the heat efficiency in the compressor can be improved. As a result, the partial load operation range in which the compressor can be operated efficiently can be widened.
According to an embodiment of the present invention, the gas turbine exhaust gas recirculation type gas turbine apparatus comprises: a compressor for compressing air; a combustion chamber for burning compression air exhausted from the compressor and fuel; a gas turbine driven by gas turbine exhaust gas from the combustion chamber; a recirculation path for recirculating a part of the gas turbine exhaust gas to an intake of the compressor; a recirculation amount control unit for adjusting an amount of gas turbine exhaust gas to be returned to the intake of the compressor corresponding to a change in load of the gas turbine; and a spray unit for spraying liquid droplets over air supplied to the compressor and gas turbine exhaust gas passing through said recirculation path so as to introduce the liquid droplets into the compressor in which the air and the gas turbine exhaust gas flow so that the introduced liquid droplets are vaporized during a flow in said compressor. As a result, in addition to the aforementioned matter, it is possible to vaporize the liquid droplets at a relative upstream portion in the compressor so that the temperature in the compressor can be continuously changed.
While suppressing a rise of the compressor exit temperature by vaporizing the liquid droplets in the compressor, the temperature of the mixing gas entering the compressor can be raised, resulting in the increase of the recirculation amount. Further, the improvement of the heat efficiency in the compressor allows the partial load operation range allowing a high efficiency operation of the compressor to be widened.
The second invention provides an exhaust gas recirculation type gas turbine apparatus comprising: a compressor for compressing air; a combustion chamber for burning compression air exhausted from the compressor and fuel; a gas turbine driven by gas turbine exhaust gas from the combustion chamber; a recirculation path for recirculating a part of the gas turbine exhaust gas to an intake of the compressor; a recirculation amount control unit for adjusting an amount of gas turbine exhaust gas to be returned to the intake of the compressor corresponding to a change in load of the gas turbine; a spray unit for introducing liquid droplets into an interior of the compressor in which mixing gas comprising gas turbine exhaust gas passing through the recirculation path and air flows so as to vaporize the introduced liquid droplet during a flow in said compressor; and a spray amount control unit for controlling a spray amount of the liquid droplets corresponding to the recirculation amount.
While suppressing a rise of the compressor exit temperature by vaporizing the liquid droplets in the compressor, the temperature of the mixing gas entering the compressor can be raised, resulting in the increase of the recirculation amount. Further, because the heat efficiency in the compressor can be improved, the partial load operation range allowing a high efficiency operation of the compressor can be widened.
The compressor intake temperature and exit temperature change are dependent on the recirculation amount, and thereby the spray amount can be appropriately adjusted.
As a result, by spraying the liquid droplets to intake air introduced into the compressor on demand by means of a simple apparatus suitable for the actual purpose so that the introduced liquid droplets are vaporized in the compressor, the widening of the partial load operation range and improvement of the efficiency of the combined cycle plant can be achieved.
The third invention provides an exhaust gas recirculation type gas turbine apparatus comprising: a compressor for compressing air; a combustion chamber for burning compression air exhausted from the compressor and fuel; a gas turbine driven by gas turbine exhaust gas from the combustion chamber; a recirculation path for recirculating a part of the gas turbine exhaust gas to an intake of the compressor; a spray unit for introducing liquid droplets into an interior of the compressor in which mixing gas comprising gas turbine exhaust gas passing through the recirculation path and air flows so as to vaporize the introduced liquid droplets during a flow in the compressor; a temperature detector for detecting a temperature of air supplied to the compressor; and a control unit for controlling so that in the case of a first temperature region in which the detected temperature is set, the recirculation is executed and the spray of droplets from the spray unit is stored. In the case of a second temperature region which is higher than the first temperature region, the recirculation is executed and the spray of droplets from the spray unit is executed and in the case of a third temperature region which is higher than the second temperature region, the recirculation is stopped and the spray of droplets from the spray unit is executed.
This will easily provide a desired load efficiently regardless of the change of external temperature.
An exhaust gas recirculation type gas turbine apparatus is preferred to comprise a control unit for controlling a spray amount of droplets from said spray unit depending on a humidity of air supplied to the compressor.
In place of the third invention""s control unit, the fourth invention provides an exhaust gas recirculation type gas turbine apparatus comprising: a control unit for controlling operation so that in the case of a first temperature region in which the detected temperature is et, the recirculation is executed and spray of droplets from the spray unit is stopped, in the case of a second temperature region which is higher than the first temperature region, the recirculation is stopped and the spray of droplets from the spray unit is stopped and in the case of a third temperature region which is higher than the second temperature region, said recirculation is stopped and the spray of droplets from the spray unit is executed.
This will easily provide a desired output efficiently regardless of the change of the external temperature.
An exhaust gas recirculation type gas turbine apparatus is preferred to comprise a control unit for controlling a spray amount of droplet from said spray unit depending on a humidity of air supplied to the compressor.
An exhaust gas recirculation type gas turbine apparatus according to claim 1 further comprising a control unit for controlling a spray amount of droplet from said spray unit depending on a humidity of air supplied to the compressor.
According to a fifth aspect of the invention, there is provided an exhaust gas recirculation type gas turbine apparatus comprising: a compressor for compressing air; a gas turbine chamber for burning compression air exhausted from the compressor and fuel; a gas turbine driven by gas turbine exhaust gas from the gas turbine chamber; a recirculation path for recirculating a part of the gas turbine exhaust gas to an intake of the compressor; and a carbon dioxide gas removing unit installed in a flow path of gas turbine exhaust gas for reducing the concentration of carbon dioxide gas in the gas turbine exhaust gas discharged after air containing the recirculated exhaust gas is introduced to the gas turbine chamber.
As a result, carbon dioxide (e.g., DO2) can be removed effectively while achieving a high efficiency operation. Further, the size of the carbon dioxide removing unit can be reduced. Because the pressure loss of the gas turbine exhaust path can be reduced by the miniaturization, the efficiency drop during the gas turbine operation can be suppressed thereby contributing to the high efficiency operation.
The carbon dioxide gas removing measure can be disposed between a diverging portion of the recirculation path of the gas turbine exhaust gas path and an emitting portion for emitting the gas turbine exhaust gas. As a result, the gas turbine exhaust gas containing high concentration carbon dioxide gas can be removed, so that the carbon dioxide gas removing efficiency can be maintained at a high level in addition to the aforementioned effect. Further, because the pressure loss can be further reduced, the high efficiency operation is enhanced.
Alternatively, the carbon dioxide gas removing measure can be disposed between the gas turbine of the gas turbine exhaust gas path and the diverging portion of the recirculation path. As a result, a large amount of the gas turbine exhaust gas can be supplied so that the carbon dioxide gas removing efficiency can be maintained at a high level in addition to the aforementioned effect.
Moreover, the carbon dioxide gas removing measure can be disposed on the recirculation path. As a result, the carbon dioxide gas removing unit can be installed easily. Further, the maintenance work for this unit is facilitated. Further, the pressure loss at a discharge portion of exhaust gas to the air can be reduced, the efficiency drop of the gas turbine can be further suppressed.